Large screen display of digital high definition (2K) and digital ultra high definition (4K) are playing more and more important role. However, the display screen is with black lattice/bezel having no video after it is spliced into large screen. FIG. 1 is four spliced liquid display screens with 2 rows and 2 columns (the diagonal is 120 inches after splicing). If a circle having 4 gaps and cross (the same width with black lattice/bezel) is input into the center of spliced screens with 2 rows and 2 columns (see FIG. 2), the 4 gaps, cross and video image having the equivalent width with black lattice/bezel cannot be displayed (see FIG. 3). If the input signal is displayed completely, it is unacceptable as the input video image is divided and the width of black lattice/bezel becomes a part of video image (see FIG. 4). So images of input video are replaced or occupied by the width of black lattice/bezel after splicing display screen with black border/bezel having no video. It is a fatal flaw for data display, curve, track, global positioning and the like.
And many obstacles are existed in some aspects such as investment scale, production equipment, material strength, yield, transportation and installation to manufacture overall display screen over 120 inches and also it is not economical. Cost per area of overall screen with 80˜120 inches will grow exponentially with the size of screen, and the cost of spliced screen will increase linearly with splicing area, that is, the cost per area is basically unchanged.
Different types of display screen used for splicing black lattice/bezel having no video are as follows.
1.0.0 Liquid Crystal Display (LCD) Screen
LCD is the most widely used display screen, and it has reached digital ultra high definition (4K). However, the edge with signal circuit is around displayable area of LCD screen c, and no video is displayed on the edge (one side is 2˜4 mm, both sides are 4˜8 mm after splicing). No matter how narrow, the edge is, the black lattice/bezel still remains after the LCD screens are spliced into large screen (see FIG. 5). Two modes are carried out to avoid these black lattice/bezel, that is, passive mode and active mode.
1.1.0 Passive Mode
The black lattice/bezel is covered visually by using optical principle of reflection or refraction for passive mode, the originally input image occupied by the black lattice/bezel cannot be restored to be displayed. Generally, there are some types as follows.
1.1.1 Reflection of Light
The originally black border a is covered by the reflector surface d with angle of 45 degrees of periphery and LCD screen c, for the repeated display e of video near the edge of the black border a in the displayable area of LCD screen c in the reflector surface with angle of 45 degrees, thereby a visual effect without black lattice/bezel is reached (see FIG. 6). However, the 4 gaps and cross of originally input video still cannot be displayed (see FIG. 7).
1.1.2 Amplification (see FIG. 8˜12)
a) the originally LCD screen c is covered by a manufactured material having same size with the LCD screen and certain thickness using the transparent material f, and an arc is made around the edge of the transparent material f along the direction of thickness, the arc has effect of amplifying the video around the displayable area of the LCD screen c. (See FIG. 8)
b) a transparent arc cylinder h is manufactured directly, the arc cylinder is attached on the black border a of the LCD screen c after the LCD screen c is spliced.
For above modes, the amplifying effect of the arc for the video around the displayable area of the LCD screen has effect of partly covering the black lattice when watching from an angle perpendicular to the bottom side A of the arc.
But the black lattice/bezel of LCD screen is wider due to the amplification of the arc when watching from an angle not perpendicular to the bottom side B of the arc, and the width of black lattice/bezel will grow with the increase of the angle, FIG. 11 is a view angle of 30 degrees, FIG. 12 is a view angle of 45 degrees, and FIG. 13 is a view angle of 60 degrees.
While for LCD large screen having several meters, decade meters or even larger, it is impractical for every display area to watch from a perpendicular angle. So when watching the spliced large screen in the form of reflection of light, the wider black lattice/bezel than originally LCD screen will appear except the display area perpendicular to the bottom side of the arc, and some defects appear,
a) The splicing quantity and size of liquid crystal display screen are limited.
b) The originally video image replaced or occupied by the black border/bezel cannot be restored to be displayed.
c) The watch mode is limited,
1.1.3 Optical Amplification Flat Panel
Based on the principle of optical fiber transmission, the optical amplification flat panel i is to transmit the pixel pitch of the light input layer (bottom layer) identically into the light output layer (top layer) with a certain equidistance, for a one-to-one correspondence between the bottom layer and pixels of LCD screen c, and the top layer is enlarged to the outer diameter having black border/bezel a of LCD screen (see FIG. 14).
1.1.4 White
To avoid the visual impact of the black and the contrast between display area and the black, the black of black border/bezel is changed into white or silver gray for the impact reduction, however, when black elements are expressed by the originally input video, visual impact still remains for white border/bezel,
1.2.0 Active Mode
For the active ode, the video image replaced or occupied by the black lattice/bezel is restored to be displayed, on the width surface of black border/bezel having no video, so that the video image restored to be displayed on the width surface of black border/bezel is fused with the video image on the displayable area of LCD screen into the video image as the originally input. This is an edge display, and the pixel need to be restored to be displayed can be realized by LED, OLED or corresponding circuit, the essentially difference with other modes of covering the black lattice/bezel is the video image replaced or occupied by the black lattice, bezel is restored to be displayed (see FIG. 15)
Besides above LCD screen, the black lattice/bezel of other display screens after splicing is demonstrated as follows.
2.0.0 Digital Light Processing (DLP) Display Screen
DLP is to manufacture the display screen using the mode of rear projection. The projection screen is fixed on the very thin frame end, so the black border/bezel a having no video of DLP is narrower (one side is 1.5 mm, both sides are 3 mm after splicing).
No matter how narrow the black border/bezel, the black lattice/bezel still remains for the DLP after splicing. And compared with LCD, DLP is the older generation of display technology with many limits and defects, such as low light, low resolution (unable to do high definition and ultra high definition), short lifetime, high maintenance cost, great thickness and need maintenance space at the rear.
3.0.0 Plasma Display Panel (PDP)
PDP is a self luminous pixel display technology, so these self luminous pixels can be manufactured on the very edge of display screen. However, these self luminous pixels still need to be supported, so the structure thickness supporting these self luminous pixels is the black border/bezel having no video (one side is 1.5 mm, both sides are 3 mm after splicing).
Meanwhile, PDP is with many limits and defects, such as burning pixel, low resolution (unable to do high definition and ultra high definition), low light, short lifetime, high price and great power consumption (see FIG. 17).
4.0.0 LED Screen
LED screen is very common. However, high definition (2K) display is difficult for LED display screen, and ultra high definition (4K) display is more difficult. The pixel pitch of LED display can reach 1.9 mm, for the digital high definition standard for screen with 1920×1080 resolution, the high definition (2K) video image can be completely displayed when the size of LED screen reach 2052×3648 mm, that is, (1.9×1920)×(1.9×1080), but some problems will appear.
a) The video image is beginning to be fuzzy when the high definition image is displayed on the screen with 2.0×3.6 meters,
b) 2 million three-color LED particles are needed for the LED screen with 2.0×3.6 meters, that is, 277 thousand independent three-color LED particles are needed per square meter, which is great challenge to the price, power consumption, heat, uniformity, reliability and lifetime.
5.0.0 OLED
OLED is a new display technology, however, it is during experimental stage at present. Large screen with several meters or decade rater manufactured by OLED remains to be seen.
In conclusion, seamless splicing cannot be truly achieved by LCD, DLP and PDP with black border/bezel for the moment, that is, the spliced LCD, DLP and PDP will produce black lattice/bezel.